1. Field of the Invention
The present invention relates to content addressable memory (CAM) arrays. More specifically, the present invention relates to a content addressable semiconductor memory array in which a single line is used for supplying power and for sensing signals associated with each row.
2. Background of the Invention
Content-addressable memories simultaneously compare a search word with a plurality of stored words. If a search word matches a stored word, an indication of the match and which of the stored words was matched is provided. A significant distinguishing characteristic of a content-addressable memory is that each stored word is uniquely identified on the basis of the value of the information stored, rather than by the address of the stored word as in conventional digital memories. Since the search word is compared to all stored words in parallel, the time needed to compare a search word to a number of stored words, known as the memory search time, is significantly reduced relative to conventional digital memories.
In operation, each bit of each stored word is stored in a discrete memory cell. Signals representative of the bits of a search word are simultaneously applied to the memory cells storing the corresponding bits of the stored words. The memory cells corresponding to a stored word are interconnected to a single sense line for providing a signal on this line in response to the stored word matching the search word. An illustrative example of a prior art CAM can be found in "Integrated-Circuit Content-Addressable Memories" by James T. Koo, IEEE J. Solid-State Circuits, vol. SC-5, pp. 208-215, October 1970.